Note: Descriptions are shown in the official language in which they were submitted.
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METHOD OF MAKING A CATHETER WITH X-RAY OPAQUE MARKINGS
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BACKGROUND OF THE INVENTION
As iS well-known, it is often necessary to
determine the depth of penetration or the position of a
particular portion of a catheter, such as the distal tip or
fluid inlet or outlet openings, after the catheter has been
inserted into the body of a patient. For this reason,
plastic catheters have been provided with at least portions
thereof formed of x-ray opaque materials. For examplej x-ray
opaque material can be mixed with the plastic and the mix-
ture extruded to form a catheter which is entirely x-ray
opaque, although the cost of the materials is relatively
high. Where it is not necessary or desired to make the
entire catheter opaque, x-ray opaque material can be added
to the plastic at selected intervals during its extrusion.
Also, plastic with x-ray opaque material can be extruded onto
the catheter or in its wall to form a stripe which, if
desired, may be interrupted in selected areas. With these
methods, the location and/or configuration of the desired
x-ray opaque markings are limited by the capabilities of
the extrusion process. In U.S. Patent No. 3,605,750, a
separate part, which may also be an extrusion, is formed of
; plastic and x-ray opaque material and fused or attached by
heat and pressure to a plastic catheter. This latter
method is relatively expensive since it involves the making
and handling of separate parts, and the fuslng of them
to selected areas on the catheter.
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SUMMARY OF THE INVENTION
Accordingly, it is an object of the present
invention to provide an improved method of making a plastic
catheter having a selected area which is x-ray opaque
wherein the catheter is relatively economical and the
form or shape of the x-ray opaque area is not limited by
extrusion process restrictions.
The invention in its broader claimed aspect
comprehends a method of making an elongated medical catheter
having an x-ray opaque marking comprising the steps of:
extruding an elongated plastic tubular member, then coating
a selected surface area of the tubular member with a mixture
while leaving other areas free of the mixture, the mixture
including an x-ray opaque material and a solution, the solution
comprising a plastic material and a solvent therefor,and solid-
ifying the coating in situ to provide an x-ray opaque marking on
the tubular member. The marking is formed in its entirety from
the mixture and the solution is in liquid form when at room
temperature prior to the step of solidifying the coating,
and the solvent is also a solvent for the plastic material
of the tubular member.
These as well as other objects and advantages of
the present invention will be apparent from the following
detailed description and accompanying drawing wherein like
reference characters refer to like parts.
` BRIEF DESCRIPTION OF THE DRAWING
Figure 1 is an elevational view of a catheter made
i` - in accordance with the present invention;
Figure 2 is an elevational view of a modified form
of catheter made in accordance with the invention;
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Figure 3 is an elevational view of a part of a
modified form of catheter or rod made in accordance with
the invention; and
Figure 4 is an elevational view of a part of a
still different form of catheter or rod made in accordance
with the invention.
DESCRIPTION OF THE PREEERRED EMBODIMENT
Referring now to the drawing, a thoracic catheter
10 is shown for illustration in Eigure 1 in the form of an
open-ended elongate plastic tube having a lumen 12 and a
plurality of holes or eyes 14 in the side wall of the tube
which communicate with the lumen 12 near the upper or
~ distal end 15 of the tube. The catheter has an enlarged,
- generally conical, lower or proximal end 16 which serves
as an adaptor for connection with another device such as a
drainage tube. The lower end 16 is beveled at 18 to
facilitate placement of the catheter following chest surgery.
In the case of a thoracic catheter, such as catheter
10, it is desirable or necessary to position or determine
the position of the most proximal eye relative to the chest
wall by means of x-ray observation. For this reason, the
catheter 10 is provided with a layer or film of an x-ray
opaque material indicated at 20. The layer 20 is in the
form of a closed or annular ring extending around the
periphery of the proximal eye, that is, the eye 14 which is
farthest from its distal end 15.
The layer 20 thus serves as an x-ray opaque marking
which can be seen by x-ray observation, such as by x-ray
film, fluoroscope, or the like, so that the catheter 10 may
be positioned to precisely locate the most proximal eye 14
in a desired location after insertion of the catheter into
a patient.
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1064337
The catheter 10 may be made by extruding a suitable
plastic material, cutting or punching the desired openings
therein, coating a selected surface area of the catheter with
a mixture which includes a liquid plastic material and an
x-ray opaque material, and then solidifying the applied
coating in situ to provide the x-ray opa~ue layer or marking
20. The coating can be applied by means of a brush, offset
printer, nozzle, or by any other suitable means for applying
the liquid coating to the catheter. Depending upon the
particular type of plastic, the applied coating may be
solidified in situ by drying, jelling, or curing.
Catheter 10 is preferably formed of polyvinyl
chloride, and the marking 20 is preferably formed of a
solidified mixture of polyvinyl chloride and an x-ray opaque
material such a$ tungsten powder. Since the plastic materials
; of the tube and the x-ray opaque marking 20 are of the same
kind, excellent adhesion of the marking layer to the
tube is obtained.
The marking 20 may be applied by preparing a mixture
of conventional polyvinyl chloride compound, such as in
pellet form, and tungsten powder in a suitable solvent, such
as cyclohexanone. For example, equal amounts of
;~ polyvinyl chloride pellets and tungsten powder, by weight,
can be mixed with an amount of solvent for the plastic that
will provide a mixture of desired consistency or viscosity
^ to allow the mixture to be easily applied to the
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selected areas or surfaces of the plastic tube, for example,
by brushing or offset printing. The mixture may be one
of very low viscosity, such as a thick paste, or it may be
a thin or highly viscous mixture. After the desired surface
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of the catheter has been provided with a coating of the
mixture mentioned above, the coating is solidified by air-
drying to drive off the solvent and produce a dry layer of
x-ray opaque material tenaciously adhering to the tube.
Alternatively, a plastisol of polyvinyl chloride
mixed with tungsten powder may be applied to the polyvinyl
chloride tubing by brushing it on or by any of the other
methods mentioned above. In this case, the liquid coating
of tungsten and plastisol is jelled or heat cured in situ
to solidify it by heating the liquid coating to its jell
temperature, which temperature will depend upon the
particular plastisol used. Such plastisols are, of course,
well-known and commercially available. Some plastisols,
for example, jell between about 150 and 180F. A typical
plastisol includes polyvinyl chloride and di-octl-phthalate
(DOP~.
In Figure 2 there is shown a catheter 22 which is
of the umbilical artery type and which is also preferably ~ -
formed of polyvinyl chloride. In this case, the catheter
is provided with an enlarged conical end 24 adapted to
receive the end of a tube or other device. The catheter 22
is provided with three dots 26 of x-ray opaque material which
may serve as marks forgauging the depth of insertion of
the distal end portion of the catheter into a patient.
- These dots can be of the same material as that of the
layer 20 of Figure 1, and can be applied in the same manner -
as layer 20. The upper distal tip of catheter 22 is
provided with a coating 28 which may be of the same x-ray
opaque material as the dots. The upper end portion of
catheter 22 may be, for example, dipped in the mixture
containing liquid polyvinyl chloride solution and tungsten ~-
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1064337
powder so that the inner and outer walls at the
upper end of the catheter and the tip end of the catheter
are coated.
Figure 3 shows a fragmentary portion of a rod or
catheter 30 for insertion into the body which has a closed
ring 32 of x-ray opaque material adhered to its outer
surface. In Figure 4, a stripe 34 extends lengthwise on a
plastic tube 36 to provide an x-ray opaque stripe which may
either be continuous from one end to the other or interrupted
to provide a series of lines. The tubes 30 and 36 in Figures
3 and 4 can be formed of polyvinyl chloride so that a mixture
of liquid polyvinyl chloride solution and tungsten powder
may be applied and solidified to form the marks 32 and 34.
When the markings 20 in Figure 1, 26 and 28 in
Figure 2, 32 in Figure 3, and 34 in Figure 4 are provided by
, applying the mixture containing the x-ray opaque material -~
and solution of plastic and solvent therefor, the coating
can, of course, be air-dried, such as by heated air, to
solidify 'he coating. When the above-mentioned mixture
containing liquid plastisol is uYed, the coating forming
these markings is solidified by raising it to the jelling
or curing temperature, as previously mentioned.
When polyurethane tubing is to be provided with
x-ray opaque markings, a conventional dipping solution of
polyurethane compound may be provided with x-ray opaque
material, such as tungsten powder, and applied in any
suitable manner to the polyurethane tubing. After the
mixture is applied, it is then air-dried or dried in a heated
` atmosphere to provide a solidified polyurethane and tungsten
layer which tenaciously adheres to the polyurethane tubing
and serves as an x-ray opaque marking.
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If the plastic tubing is made of silicone
rubber, a mixture of conventional silicone rubber compound
and x-ray opaque material, such as tungsten, in a suitable
solvent for the rubber such as Toluene or Xylene, may be
applied to the tubing. The applied coating is solidified
such as by drying, for example, in an oven to remove the
solvent, and is then heat cured. In this manner, suitable
x-ray opaque markings which adhere to the silicone rubber
catheter are provided.
Other well-known x-ray opaque materials such as
barium sulfate or tin, as well as others, may be used
instead of tungsten powder. Also, the polyvinyl chloride
compound may contain softeners and stabilizers.
By applying a mixture which includes a plastic
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~` solution and x-ray opaque material to the catheter or rod,
f a great variety of markings can be readily obtained in a
simple and economical manner.
Various other well-known additives, such as fillers,
,~ colors, etc., may be added where desired to the liquid
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containing the plastic and x-ray opaque material.
While a preferred form of the invention has been
~' described herein, it will be apparent that various changes
and modifications thereto may be made without departing from
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~ the spirit or scope of the invention as defined in the ~
,~ appended claims. -
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